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I propose adding n cat lab tag as in https://ncatlab.org/nlab/show/HomePage.
As https://ncatlab.org/nlab/show/HomePage has large amount of mathematics used as reference and/or as in learning for the first time I guess it would be useful to have a tag.
Questions in this tag should be restricte...
Let $A$ and $D$ be two abelian groups and $B,C$ be two non-abelian groups. Also, let $C$ acts on $A,B,D$.
Let $0\to A \xrightarrow{f}B\xrightarrow{g}C\to 0$ be a short exact sequence of groups in which the action of $C$ commutes with maps $f$ and $g$ ($C$ acts on itself trivially). Also, let...
